Interferons, and the leukocyte interferon inclusive, are essentially a class of inducible proteins in the vertebrates that are capable of exhibiting antiviral and antimicrobial activity, participating in regulation of immunological reactions of a cell and producing radioprotective and antitumorigenic effect. Human leukocyte interferons make up a multigene family incorporating not less than twelve members, which has been proved by an analysis of the structure of the chromosomal DNA and cDNA synthesized on the interferon mRNA, as well as by that of the aminoacid sequence of individual proteins from a heterogeneous mixture of human leukocyte interferons.
Known in the present state of the art are diverse human leukocyte interferons obtained by virtue of genetic engineering, e.g., interferon A produced by recombinan DNA in the cells of Escherichia coli (cf. Goeddel D. V. et al., Human leukocyte interferon produced by E. coli is biologically active, Nature, 1980, 287, 411-416), or human leukocyte interferon F (cf. Ovchinnikov Yu. A. et al., Direct expression of the gene of human leukocyte interferon F in the cells of E. coli, Transactions of the USSR Academy of Sciences, 1982, 265, 238-242 (in Russian), which is in effect a protein consisting of 166 aminoacids arranged in the following sequence:
CDLPQTHSLGNRRALILLAQMGRISPFSCLKDRHDFGFPQEEFDGNQFQKAQAISV LHEMIQQTFNLFSTKDSSATWEQSLLEKFSTELNQQLNDMEACVIQEVGVEETPLM NVDSILAVKKYFQRITLYLTEKKYSPCAWEVVRAEIMRSFSLSKIFQERLRRKE
A-ala; C-cys; D-asp; E-glu; F-phe; G-gly; H-his; l-ile; K-lys; L-leu; M-met; N-asn; P-pro; Q-gln; R-arg; S-ser; T-thr; V-val; W-trp; Y-tyr.
To produce the aforesaid interferon F the summary messenger RNA is produced from human blood leukocytes induced by Newcastle disease virus using the guanidine-chloride-guanidine-thiocyanate method. The poly-A fraction of mRNA is produced by double purification on oligo-dT-cellulose. The synthesis of cDNA is carried out using a synthetic oligonucleotide complementary to the gene of interferon within the sphere of translation termination. The synthesis of the second chain is performed with the aid of the Klenov's fragment of DNA-polymerase I. The thus-produced double-chain DNA is inserted after reconstruction, in the vector plasmid pBR 322 under the control of a tryptophane promotor. It is with the aforesaid recombinant plasmid that the E coli cells are transformed.
The aforementioned human leukocyte interferons differ from each other both in the efficacy of an inhibitory effect they produce on the cytopathic action of the same virus, and in the potency against most various viruses.